Japanese Spacecraft Deploys First-Ever Solar Sail

The unfurling of a Japanese solar sail, the first demonstration of a new space propulsion technology, went exactly according to plan.

According to JAXA’s blog posts and photos from the event, the IKAROS spacecraft’s sail appears to be in place. It’s a big step in its attempt to travel driven only by sunlight.

“This is the first sail ever deployed in space, and if they succeed in using it for solar-sail flight — it’ll still be a few weeks before we know that — it’ll be a milestone,” said Louis Friedman, executive director of the Planetary Society, an organization dedicated to promoting space exploration, which is readying its own solar-sailing mission.

A solar sail uses the pressure from photons striking its surface to push the spacecraft through space. Materially, the 650 square-foot sail is made of incredibly thin, aluminized plastic that’s only 0.0003 inches thick, a little thicker than spider silk, or about the diameter of a red blood cell. When a photon strikes its surface, it bounces off, imparting its momentum to the sail. Each photon might not deliver much thrust, but over time, all that light adds up.

“The actual force might be just a few millionths of a g, but because it acts continuously, it allows you to build up large velocity changes over time,” Friedman said. “That’s where a sail really does its work is long missions.”

I really hope that the sail and that it can be powered by the sun, it would really make a difference in the way we explore the universe in the future.